Officials battling a wildfire in Northern California that has become the state’s deadliest of the year so far are fearing the death toll could rise further Friday as at least 16 people remain missing.

There are at least 15 people reported dead across California, Oregon and Washington as wildfires continue to rage in all three states.

The North Complex fire as of this morning has burned more than 244,000 acres near Oroville and is only 23% contained, according to Cal Fire. But authorities say it is now advancing more slowly Friday as winds have eased and smoke from it has shaded the area and lowered the temperature, allowing firefighters to make progress.

Among those unaccounted for are Sandy Butler and her husband, who had called their son to say they were going to try to escape the flames by finding shelter in a pond.

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“We’re still hoping and praying for good news,” Jessica Fallon, who has two children with the Butlers' grandson, told the Associated Press. “Everything is replaceable, but not my grandparents’ lives. I’d rather lose everything than those two. They kind of held the family together.”

Fallon said she’d been peppering hospitals with phone calls in search of her grandparents, but as of late Thursday night, there was no word of them.

A hand crew clears vegetation from around a barn as the Bear Fire -- which is now part of the North Complex fire -- burns through the Berry Creek area of Butte County, Calif., on Wednesday. (AP)

A hand crew clears vegetation from around a barn as the Bear Fire -- which is now part of the North Complex fire -- burns through the Berry Creek area of Butte County, Calif., on Wednesday. (AP)

On Thursday, Butte County Sheriff's Capt. Derek Bell said the North Complex fire death toll reached 10 and four people have been hospitalized after suffering critical burns.

He added that deputies and detectives are searching for human remains as they make their way into devastated areas with a team of anthropologists from Chico State University.

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More than 2,000 homes and other buildings have burned so far in the fire, which began several weeks ago as a lightning-sparked collection of blazes northeast of San Francisco. The final toll is expected to be much higher and damage assessment teams planned to begin a methodical search of the burned areas on Friday.

President Trump has spoken with Gov. Gavin Newsom “to express his condolences for the loss of life and reiterate the administration’s full support to help those on the front lines of the fires,” White House spokesman Judd Deere said.

Neighboring Oregon and Washington also have been besieged by wildfires.

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Eden McCarthy pets her dog Hina in the rubble of her home destroyed by the Almeda Fire on Thursday in Talent, Ore. (AP)

Eden McCarthy pets her dog Hina in the rubble of her home destroyed by the Almeda Fire on Thursday in Talent, Ore. (AP)

More than 1,400 square miles have burned this week in Oregon, where hot, windy conditions are continuing. Authorities said more than 500,000 people -- more than 10% of the state's population -- have been forced to evacuate.

Oregon officials haven’t released an exact death count for the wildfires but at least four fatalities have been reported in the state.

The Associated Press says officials there are shocked by the number of simultaneous fires, which stood at 37 as of Thursday, according to the state Office of Emergency Management.

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Gov. Kate Brown said more than 900,000 acres -- greater than the size of Rhode Island -- have burned in Oregon over a three-day stretch this week, which is nearly double the territory that burns there in a typical year.

One person was killed in wildfires in Washington, which have scorched nearly 937 square miles.

The Associated Press contributed to this report.